The "Royal Canadian Mounted Police" do not wear the classic red serge jackets, that's only for special events and even there there's only a handful of them. The "mounties" on duty in the movie should be wearing normal police style uniforms in dark colors. The production had the uniforms completely wrong and almost comedic.
Upon discovering that their fellow CBP officers were killed, the proper protocol for the two officers who discovered the murders would have been to immediately draw their firearms to safeguard against a remaining potential threat AND to radio or phone for backup. The backup that arrived would have been substantial in the form of a sea of CBP officers and Border Patrol agents, with state, provincial, and local police arriving on "both sides of the border" to begin canvassing the area for the dangerous suspects. Instead, the two officers violated CBP's departmental protocol by not calling for backup, and pursuing the assailants by themselves through a dark forest. Not surprisingly, this ended up being a costly mistake.